Forums DIY Ground Source Heat Pumps Reply To: Ground Source Heat Pumps October 25, 2018 at 2:38 pm #434 burton 25 Posts That’s probably the other realistic option. Lower initial cost, and it would mean we didn’t need to dig up the whole garden. At this stage I’d prefer a heat pump for 2 reasons 1. It’s more environmentally friendly 2. Installation costs are likely to work out way cheaper in the long run thanks to the RHI subsidy.